Rock drilling core bit



April 2, 1935; A. E. CARLSON 1,996,322

ROCK DRILLING CORE BIT April 2, 1935- l A, E. CARLSON 1,996,322

Rock DRIILING CORE BIT Filed July 24, 1931 5 Sheets-Sheet 2 Fuz' April 1935. A. E. CARLSON l ROCK DRILLING CORE BIT Filed July 24, 1931 5 ISheets-Sheet 3 Av" (W E Patented Apr. 2, 1935 UNITED STATES ROCK DRILLING C ORE BIT Anthony E. Carlson, Los Angeles, Calif. Application July 24, 1931, Serial No. 552,813

y, l 17 Claims. (Cl. Z55-72) My invention relates to rotary well drilling equipment, and relates particularly to a core bit especiallysuitable for penetrating hard formations.

y In the past hard formations, such as rock, required the use of roller type drilling bits in which the rollers were provided with sharp teeth which produced a crushing action on the rock, thus slowly disintegrating it to powdered form. 'I'he I drilling speed of such bits is very slow owing to the fact that the bit is required to break down or out away a volume of rock equivalent to the volume .of the hole drilled through -such rock.

My invention comprehends a rock drilling bit which will cut an annular opening so as to leave a core in the center in the same manner as core bits now employed for taking core samples in the drilling of a well. Accordingly, by the use of my bit the speed of drilling a hole of a given diam' eter through a rock formation is greatly increased for the reason that the entire volume of rock material taken from the hole is not disintegrated by the roller cutters of the bit, but the core which is formed is removed in a single piece to the surface of the ground when the bit is lifted from the well.

This principle of increasing the drilling speed through rock by drilling an annular opening and bodily removing the core thus formed has been recognized by engineers for some time, but many ditliculties in making a satisfactoryrock rollercore bit have been encountered. f In order to prevent lateral oscillation.- or vibrationl which repeatedly breaks olf the Acore so that it packs in the core barrel in chunks and interferes with the progress of the drilling operation, such a large number of rollers have been employed that the size of these rollers is reduced to such an extent that the drilling capacity thereof and their useful lii e in the well are greatly reduced, with the result that even though a core" was being formed, the reduced speed and short life yof small rollers prevented a material increase in the overall drilling speed as compared with the overall drilling speed of standard roller-type rock bits.

`In my new rock core bit a relatively small number of large roller cutters are employed, the number adapted for generaluse being four, two of which are sloped inwardly and two of which are sloped outwardly. This has been considered too small a number of rollers for use in a rock roller bit, for the reason that a core bit with such a small number of rollers would operate with such It is a feature of my improved rock core bit toi employ a small number of large roller cutters and 1 an auxiliary means located above and close to the cutting plane for preventing side-sway or oscillation destructive to cores. This stabilizing or 5 guiding means may be in the form of a reamer or a non-cutting guide member which frictionally engages the wall of the hole at a point close to the cutting plane and wears down periph,- erally at about the same rate as the outer parts 10 of the cutters wear so that asthe size of the hole decreases due to cutter wear,the diameter of the guide meansdecreases accordingly, and excessive frictional loads are thereby avoided. The stabilizer also serves as a centering guide as the bit 15 is moved through a casing set in a well.

It is a further object of my invention to provide a core drilling bit consisting of a tubular head and a sub-head which Vcarries the cutters secured to the lower end thereof. This sub-head 20 is readily removed from and replaced on the main head and holds in place a replaceable stabilizer 4or guide member of the character above set forth.

It is an object of my invention to provide ai A lcore bit for rock drilling which, for the purpose 35 of periodically cleaning the cutters, may be raised from the bottom of the hole without danger of breaking `oif the core. This is accomplished by inclusion in my invention of my improved and novel forml of core catcher which adheres to the 40 core and is disposed ina vertically elongated annular space inthe'lower end of the core bit.

A further object of the invention 'is to provide a core bit construction in which the waterways may be conveniently formed and Iin whichA such 45 waterways effectively distribute the drilling uid.

A further object of 'my invention is to provide a bit vbody having recesses therein in which roller reaming cutters are mounted, this bitbody having simple means for holding in place the 50 parts of the reamer assemblies and being of simple and economical construction by reason of the simple and economical manner in which the recesses or chambers for receiving the roller reaming cutters may be formed therein. 5K5

A further object of my invention is to provide a bearing construction which will enable the bit to operate with a minimum of friction and to provide a simple bearing and bearing pin construction for the roller cutters and a novel and simple means for securing the bearing pins in place.

It is a. further object of the'invention to provide a rock core bit of the above character having such construction that the roller cutters thereof cut a large clearancel around the body of the bit, this result not being attainable by any of the rock core bits now on the market. f,

Further objects and advantages of the invention will be made evident throughout the following part of the specification.

Referring to the drawings, which are for illustrative purposes only, f

Fig. 1 is an elevational view in quarter-section showing a preferred embodiment of my invention with the inner cutters thereof removed.

Fig. 2 is a partly sectioned side view of Fig. 1 viewing the .bit shown inl Fig. l at an angle of from the line of vision on which Fig. 1 is viewed, the outer cutters being omitted. F1Fig. 3 is a bottom plan view corresponding to Fig. 4 is a cross-section on a by the line 4-4 of Fig. 1.

Fig. 5 is a cross-section on a by the line 5 5 of Fig. l. f Y

Fig. 6 is a cross-section on a plane represented by the line 6-6 of Fig. 1.

Fig. 7 is an enlarged fragmentary section taken as indicated by the line 1-1 of Fig. 2.

Fig. 8 is' an enlarged fragmentary sectional view showing an alternative form of cutter and bearing-construction and an improved means for securingthe bearing pins in place.

Fig. 9 is an enlarged fragmentary sectional view plane represented showing an alternative method of securing the bearing pins/in place as applied to an external cutter assembly.

Fig. 10 is a fragmentary section taken as indicated by the line I II-IIl of Fig. 9.

Fig. 11 is an enlarged fragmentary sectional view showing an alternative form of bearing pin securing means as applied to an internal cutter.

Fig. 12 is a vertically sectioned view of the upper end of the drill bit, showing the check valve at the upper end of the core receiving liner.

As best shown in Figs. 1 and 2, the preferred embodiment of my rock drilling bit includes a sub-head I5 and a main head I6 comprised of a lower body member I1, a middle body member I8, and an upper body member I3 from the upper end 2| of which a tubular shank 22 extends, this shank 22 4being of a length correspondingto the maximum length of core desired to be cut and having a threaded upper end 23, as shown in Fig. 12, for securing it to a drill collar 24. The upper body member I 9 has a downwardly converging lower portion 26 equipped with a cylindrical bore 26 and a counterbore 21 provided with internal threads 28. 'Ihe upper end 2| of the body Il is cylindrical and is provided with a threaded counterbore Il into which the shank 22 threads. The middle body member .I8 has a central cylindrical wall 3| from which a cylindrical wall 32 of reduced external diameter extends upwardly. This .wall 32 is externally threaded soV that it will screw into the threads 28 of the counterbore 21 and has in its upper end a threaded counterbore 33. From the lower end of the cylindrical wall 3| a cylindrical extension plane represented 34 projects downwardly, this extension 34 having a cylindrical outer face of slightly smaller diameter than the outer face of the wall 3|, the outer face of the extension 34 joining the outer face of the wall 3| through a short, upwardly diverging conical face 35. Within the extension 34 a counterbore 36 is formed, the upper portion of this counterbore 36 converging upwardly with a conical face 31 to meet the bore 38 of the cylindrical wall 3|. The counterbore 36 is equipped with internal threads 40 adapted to receive an externally threaded cylindrical wall 4I which forms the upper part of the lower body member I1. The central part of the member I1 consists of an annular wall 42, the external diameter of which is substantially the same as the external diameter of the `extension 34 adjacent which it operates. The lower body member I1 has a bore 43 which is approximately the same diameter as the bore 38 of the middle body member I8 but is preferably slightly smaller. The bore 43 is preferably about six inches long and has a downwardly converging conical wall 44 at its lower end which meets a downwardly con-l verging wall 45 formed at the upper end of the central bore 46 of the sub-head I5. The lower body member I1 has a lower cylindrical wall 41 surrounding the bore 43 and the conical wall 44. 'I'his lower cylindrical wall 41 is approximately half the radial thickness of the annular wall 42 and has a downwardly and outwardly facing annular channel 48 cut in its lower end.

The sub-head I5 has an upper cylindrical wall 5I! which is of substantially the same exterior diameter as the annular wall or extension 42, and the bore 5| thereof is of such diameter that it will fit over the downwardly extending wall 41 of the lower body member I1. Downwardly adjacent the cylindricalwall 50, the sub-head I5 has a cylindrical wall 52 of larger external diameter than the wall 50 and has the corneal face 45 formed therein. A horizontal shoulder 53 formed by the inner upper portion of the wall 52 fits tightly against the lower end of the wall 41, thus converting the annular channel 48 into an annular passage between the lower end of the wall 41 and the wall 52. Downwardly projecting from the wall 52 are a pair of primary leg formations 55 and va pair of secondary leg formations 56. 'Ihe primary leg formations 55 are diametrally opposed, and the secondary leg formations 56 are also diametrally opposed on a plane 90 from the diameter defined by the primary leg" formations 55. As shown in Fig. l, the primary leg formations 55 have upwardly and inwardly sloping, tangentially directed notches 51 therein which divide the lower ends of the prlmary leg formations into outer walls or legs 58 and inner walls or legs 60. Through the legs 58 and 66 pin holes or bores 6I are formed so as to slope downwardly and inwardly in a diametral plane dened by the primary leg formations 55. 'I'he angle of slope of the pin openings 6I varies a little in the construction of different sizes of bits, but in general practice it ranges from twenty to twenty-five degrees from horizontal.v

By means of pins 62 which extend in the pin openings 6I, external cutters 63 are secured in the tangential notches 51. To prevent wear against the inner faces of the legs 58 and B0. thrust washers 64 and 65 are provided. Means are provided for preventing rotation of the thrust washers, and, as shown at 66 in Fig. 1, such means may consist of an outwardly prov.ieting wall on the lower portion of a thrust at the inner end of the bore 82.

`portion of the bore.

Washer, this projecting wall fitting into a lateral notch 61 formed in' the lower end ofthe leg 60. The secondary leg formations 56, as shown in Fig. 2, each have a downwardly and inwardly sloping tangential notch 68 therein, forming in the leg formations 56 Walls or legs 10 and 1|. Across the lower portions of the legs 10 and 1 I, upwardly and inwardly sloping pin holes or bores 12 are formed, and by means of bearing. pins 13 internal bearing assemblies 14 are supported in inclined positions in the notches 68.

In my invention I provide a novel and simple means for securing the bearing pins 62 vand 13 in place in such a. manner that they cannot become lost during operation of the bit but may be readily removed when replacement of the bearing pins and cutter assemblies is desired. Such means consists, as best shown in Fig. 7of a rivet 15 extended through an opening 16 in a supporting leg, such as a leg 60 or 10, and through an opening 11 through the bearing pin 62 or 13 which extends through the leg 60 or 10. The rivet 15 initially has a head 18 on one end, and after it is placed in position in the openings 16 and 11, the opposite end thereof is peened over to form a head 8|. The rivet cannot be lost` from the opening 16, and consequently the pin 62 or 13 cannot be lost. When it is desired to remove a pin, either head 18 or 8| may be cut Ifrom the rivet 15 and the rivet driven out. "Each cutter 63 has a bore 82 adapted to receive a complement of bearing rollers 83 `placed around a pin 62. At the inner end of each bore 82 an annular wall or flange 84 extends inwardly so as to substantially fill the space surrounding the pin 62 'Ihis annular wall 84, `being a part of the cutter 63, rotates therewith. in the direction of movement of the bearing rollers 83 which tend to creep inwardly along the pin 62 so that they engage the face of the annular wall 84. The bearing rollers 83 are thereby prevented from forcible end engagement with a stationary wall and instead are caused to engage a moving wall, thereby keeping at a minimum the retarding action due to end engagement of the bearing rollers. 'I'he internal cutter assemblies 14 each consist of a pair of cutters 85 separated by an annular washer 86. Each lof theseucutters has a bore 81 for receiving a bearing roller 88 and an inwardly directed flange 90 at the lower end of the bore for receiving the end thrust of the bearing roller 88. In the form'J of my invention shown in Figs. 1 and 2, the4 cutters and cutter assemblies 63 and 14 have been respectively termed external and internal, this being for the reason that the cutters63 form the outer or external portions of the annular bore and the cutters cut the internal or inner The cutters 63 and 85 are shown cylindrical in form, but in the practice of the invention these cutters may be readily made conical, as conditions of operation may require and as will hereinafter be illustrated in Aconjunction withother features of my invention.

To-prevent side-sway or'oscillation of the bit so as to avoid breaking off of the core 90 formed thereby, I provide a stabilizer or guide member 9| which fits between the upper end of the wall 50 and a shoulder or face 92 at the lower end of the annular wall 42. As shown in Figs. 1, 2, and 6, the stabilizer 9| consists of a: ring 93, thelower portion of which tits into an annular channel 94' formed in thelupper end of the wall 50. Projecting outwardly from the ring 93 are a plu-l rality of radially extending webs 95, the peripheral edges 96 of which are vertically rounded, as

shown in Figs. 1 and 2, and are circumferentially curved, as shown in Fig. 6, to lit the bore 91 cut by the cutters of the bit. From the outer.

threaded into openings |04 in the wall 50 and have inner cylindrical ends |05 which 'seat in recesses |06 in the wall 41. The extending of the lower portion of the ring 93 into the annular channel 94 and behind the posts 98 will effectively prevent loss of any part of the stabilizer 9| should it become broken radially. The peripheral edges 96 of the stabilizer 9| engage the bore 91 during the operation of the bit and maintain the bit in centralized position. Engagement of the edges 96 with the bore 91 results in an abrading thereof so that the diameter of the stabilizer 9| is reduced. In the stabilizer 9| the amount of metal disposed for engagement with the bore 91 may be so proportioned that the reduction in diameter of the stabilizer will be 'proportionate tol middle body member I8 is placed close to the.

lower end of the tool so that it will also have a pronounced stabilizing action supplementing the stabilizing action oi.'` the member 9|. Where the reamer is employed, the stabilizer 9| may be omitted and the reamer depended on for preventing lateral side-sway or oscillation. The construction of this reamer assembly is of especial importance to my invention as it may be readily incorporated in my bit structure without exorbitant cost. In its construction'blind recesses ||0 are formed in the cylindrical wall 3| by cutting openings I II, as shown in Fig. 4, through the wall 3| to the bore 38 thereof, and after the cutting oi' these openings, the inner ends thereof are closed by a steel sleeve I2 having an enlarged, externally threaded upper end ||3 which screws into the threaded counterbore 33 in the upper end of the wall 32. The sleeve ||2 extends entirely through the bore 38 of the cylindrical wall 3| and effectively closes the inner ends ofY the openings III, changing the. openings III to pockets or recesses in which roller-type reaming cutters I|4 are mounted on substantially vertical shafts'I I5. The shafts ||5vare replaceable, and the upper and lower ends thereof are received in openings ||6 and ||1 in the walls ||8 and |I9 forming the upper and lower ends of the recesses ||0. The openings ||6 openl onto the horizontal face or shoulder |20 formed between the-upper edge of the wall 3| and the lower end of the wall 32. Therefore, there is an open space at the outer ends of the openings ||6, when the lmiddle body member and upper body'member are with the openings |I1. When the middle body` member I8 and the upper body member I9 are reassembled, the lower end of the upper body member I9 vclosesthe upper ends of the openings II6 and preventsY removal of the shafts I I5. The shafts I|5 are held from rotation by the engagement of notches |2| in their lower ends with horizontal pins |22 which extend diametrally across the lower ends of the openings ||1. For installation of the pins |22, radial openings |23 may be drilled radially inwardly through the wall ||8 in position to diametrally close the lower portions of the holes ||1. The outer ends of the openings |23 may be then closed, as indicated at |24, by filling in a wall of metal by welding. Thepins |22 may be inserted in the openings |23 through the bore 38 before the sleeve ||2 is installed, the

lower end of the sleeve ||2 after its installationpreventing movement oi the pins |22 from the openings |23. At the upper ends of the recesses ||0 rectangular thrust washers |25 are-placed so as to receive the wear of the upper ends of the cutters ||4. From the foregoing, the simple making of areamer body by first cutting holes through a ,cylindrical walland then closing the inner ends thereof will be perceived. The holes may be cut with an oxyacetylene torch slightly undersize and then trimmed to nished size, which is very economical as compared to the cutting of a recess of the same size as the recess ||0 by theuse of millingtools.

The wall 4| of the lower body member |1 is provided with internal threads |30 which receive the lower threaded end |3| of a core receiver or barrel |32 which extends upwardly through the middle body member I8, the upper body member I8, and the shank 22. On the upper end of the core receiver |32 a reducing fitting |34 is secured, and threaded onto the reducing end |35 thereof Y is a valve cage |36 adapted to hold a valve ball |31 in position for cooperation with a valve seat |38, thus providing the upper end of the core receiver |32 with a downwardly closing check valve for preventing entrance of drilling fluid into the upper end of the core receiver |32, as shown in Fig. 12. The lower end |3| of the core receiver |32 forms a shoulder |40 at the upper end of the bore 43 of the lower body member |1, this shoulder |40 serving as a stop for the upward movement of my improved core catcher |43. This core catcher |43 consists of a contractile encircling member or ring |44 which may be conveniently formed from rubber. Secured to the ring |44, by such means as rivets |45, are a plurality of downwardly projecting jaws |46. 'I'he ring |44,

which may be also made of spring steel, is adaptwithout applying any breaking strain on the core |48, until the downwardly converging face 44- engages the jaws |46. The bit may be raised from the drilling position in which it is shown in Fig. l to the raised position shown in Fig. 2 without the face 44 engaging the jaws |48, 4and the bit may be rotated in this raised position for the purpose of running free and cleaning the cutters, which is accomplished by the drilling iiuid which passes down through the watercourse |50 and is issued through discharge openings |5|` and |5|a. The watercourse |50 includes the opening |52 of the drill collar 24 leading into the upper end |53 of the shank 22, the annular space |54 within the shank 22, the upper body member I8, and the middle body member I8, and surrounding the core receiver |32; an annular space |56 adjacent the conical face 31 of the wall 34; vertical holes |51 drilled vertically through the wall 4|, the inner portion of the wall 42, and the wall 41 of the lower body member I1; the annular space 48 communicating with the lower ends of the holes |51; and the discharge passages ISI.

The effective diameter of the bit may be readily varied within small limits by changing the thickness of the washers 65 so as to change the positions of the cutters 63. The effective-diameter of the bit may also be readily varied by replacing the sub-head I5 with one of larger diameter, replacing the stabilizer 8| to correspond with the size of the hole cut by the outer cutters 63 of the larger size head, and increasing the diameters of the reaming cutters ||4, this making it possible to use a. single main head assembly for several sizes of bits.

In Fig. 8 I show an alternative method of securing a bearing pin |60 in holes |6| and |62 formed in supporting legs |63 and |64. In this construction the pin |60 is equipped with a threaded opening |65 which is aligned with openings |66 and |61 in the supporting leg--|53. A locking screw |68 has a central threaded shank |18 of a size to t the threaded opening |65. On the inner or upper end of the screw |68 is an end or extension I1 the diameter of which is no greater than the rootl diameter of the threads on the shank |10. On the lower outer end of the shank a head |12 is formed which has a diameter no smaller than the root diameter of the threads of the opening |65. It will be perceived that the screw |68 has threaded engagement only withthe bearing pin |60 and that the cylindrical ends I 1| and |12 fit into cylindrical openings. In replacing the pin |60, a new threaded opening to receive the screw |68 is provided in the new'pin, and, if desired, the screw |68 may be also replaced. In this construction there are no threaded openings in the permanent supporting structure formed by the leg |63, and accordingly there are no permanent threads which may become worn so as to hold a locking screw loosely. By replacing one or both of the parts |60 and |68 when the cutters are replaced, it is made possible to maintain a tight ilt between the locking screw and the threaded opening into which it ts.

In Fig. 9, I disclose an external or outwardly sloping cutter |13 of conical form having bearing rollers |14 therein which turn on a bearing pin |15. Disposed in conjunction therewith is a simple and effective means` for securing the bearing pin |15 in supporting legs |15 and |11 of a supporting structure |18. The feature of this construction is that notches are formed in the lower ends of the legs |16 and |11, these notches |80 .having parallel side walls |8|, as shown in Fig. 10. The ends |82 and |83 of the pin |15 are attened to such width that they will slide upwardly in the notches |80 in close engagement with the side walls |8|. The flattened ends |82 and |83 extend inwardly a suillcient distanceto receive wear plates or thrust washers |84 vand |85 thereon. these washers |84 and |85 having openings 4|81 therein which are of the same shape as the ends |82 and |83 and are therefore prevented from rotation with the deformed ends of the pin |15. In order to make thesethrust washers |84 and |85 massive, they may becountersunk into the endsof the cutter |13, as shown. To hold the pin |15 in the open notches |80, rivets |88and |80 are passed through holes in the legs |16 and |11 and in the ends of the pin |15. Illustrative of this. I show in Fig.

10 openings 19|, |92, and |93 through which the rivet |88 is passed, whereupon the projecting end of the rivet may be peened over so that there will then be heads |94 and |95 on the exposed ends of the rivet which will prevent removal of the rivet, but either of which heads may be cut off with a chisel to permit the rivet to be driven out. In Fig. 11, I show an internal cutter assembly |96 consisting of a pair of cutters |91 and |98 which are separated by a separating washer 200. The cutters |91 and |98 have bearing bores-20| which face toward the separating washer 200 and have radially projecting iianges 202 closing their outer ends. Bearing rollers 203 which operate in the bores 20| have their ends abutting walls which rotate with the cutters |91 and |98. The .cutter assembly |96 is mounted on a bearing pin 204 which, like the bearing pin |15 of Fig. 9, has attened ends 205 and 206 which slide upwardly into notches 201 and 208 formed respectively in supporting legs 209 and 2|0. For securing the bearing pin 204, the rivet |88 is passed through the end 205 in the manner described relative to Fig. 10. By this rivet the upper face 2|2 of the end 205 is held against the upper wall 2|3 of the notch 201 so that the bearing pin 204 cannot rotate downwardly. This holding effect is also aided by the engagement of shoulders 2 I4 of the bearing pin 204 which engage a thrust washer y2|5. If desired, the end 206 may be secured by placing a small weld in the lower portion of the notch 208 adjacent the lower portion of the end 206, as indicated at 2 I1 in Fig. 11.

I claim as my invention:

1. A rotary rock core bit of the character de'- scribed, including: a cylindrical member having a bore therethrough and a counterbore at the lower end of said bore; a lower cylindrical part secured to said cylindrical member and having an internally threaded, cylindrical wall extend-v wall, the upper end of said lower cylindrical part forming a'lower end wall for said annular drilling fluid passage and said lower cylindrical part having a plurality of fluid passages leading down from the lower end of said annular passage; a tubular wall projecting downwardly from said k lower cylindrical part, said tubular wall being in the lower end thereof adapted to receive roller cutters, there being an annular channel formed between said sub and said lower cylindrical part connected to said iiuid passages of said lower cylindrical part and fluid discharge openings extending downwardly from said annular channel; and roller rock cutters secured in said notches in position to cut an annular opening leaving a core projecting up into said rock bit. A

2. A bearing for a Yroller cutter of the character described, comprising: a shaft; a cutter body on said shaft, said cutterbody having a. bearing bore of larger diameter than said shaft and an inwardly projecting radial flange at an end of said bearing bore, the inner portion of said ange approaching close to the surface of said shaft; and bearing rollers in said bearing bore, there being a plate closing the open end of said bearing bore.

3. A bit of the character described, including: a body adapted to be secured to the lower end of a string of drill pipe, said body having a slot formed between inner and outer walls; a cutter shaft extended across said slot between said inner and outer walls; and a roller cutter mounted on said shaft, said roller cutter having a bore of a size to closely t said shaft and having a counterbore extending from one end of said roller cutter to a point near the opposite end thereof, there being bearing rollers disposed around and in engagement with said shaft within said counterbore. y

4. A bit of the character described, including: a body adapted to be secured to the lower end of a string of drill pipe, said body having a slot formed between inne'r and outer walls; a cutter shaft extended across said slot between said inner and outer walls; a roller cutter mounted on said shaft, saidv roller cutter having a bore of a size to closely fit said shaft and having a counterbore extending from one end of said roller cutter to a point near the opposite end thereof, there being bearing rollers disposed around said shaft within said counterbore; and a thrust plate on said shaft in positionto close the open end of said counterbore and to receive the wear of the ends of said bearing rollers.

5. A bit of the character described, including: a body adapted to be secured to the lower end .of a string of drill pipe, said body having a groove formed between inner and outer walls, there being channels formed in the lower ends of said inner and outer walls on a plane crossing said groove, and there being a rivet opening in the lower end of one of said walls in position to intersect the channel in such wall; a roller cutter in said groove; a thrust plate adjacent an end of said roller cutter, said thrust plate having a non-circular opening therein; a shaft for holding said cutter and said thrust plate in said groove, the ends of said shaft being received in said channels, and the end of said shaft cooperating with said thrust plate, being of non-circular cross section, whereby 'to engage said thrust plate and one of said channels in anon-rotative manner, there being a rivet opening through one end of said shaft; and a rivet extended through said rivet openings whereby to hold said shaft in said channels, said rivet having an exposed head on one end thereof adapted to be cut'oif to permit removal of said rivet.

6. A bearing for a. roller cutter of the character described, comprising; a shaft; a cutter body on said shaft, said cutter body having a bearing bore of larger diameter than said shaft and an inwardly projecting radial flange at an end of said bearing bore; and vbearing rollers in said bearing bore, there being a plate closing the open end of said bearing bore.

7. A bit of the character described, including: a body adapted to be secured to a string of drill pipe, said body having a cutter recess formed'between relatively inner and outer walls, there being slotsQacross the outer ends of said walls on an axis crossing said recess; a roller type cutter in said recess; a shaft for said cutter having its ends in said slots, one end of said shaft being of attened form so as to engage its cooperating slot in non-rotative relation; and a rivet extending through one of said lwalls and across the slot therein in position to prevent removal of said shaft, said rivet having a head formed on one end` thereof adapted to be removed to permit removal thereof.

8. A bit of the character described, including: a body adapted to be secured to a string of drill pipe, said body having a cutter recess formed between relatively inner and outer walls, there being slots across the outer ends of said walls on an axis crossing said recess, one of said slots having substantially parallel side Walls; a roller type cutter in said recess; a shaft for said cutter having its ends insaid slots, one end of said shaft being of flattened form to provide parallel faces adapted to engage said substantially parallel slot walls, .and said shaft having shoulders formed thereon to transmit'lateral forces from said shaft to said body; and a rivet extending through one of said walls and across the slot therein in position to prevent removal of said shaft, said rivet having a head formed on one end thereof adapted to be removed to permit removal thereof.

9. A bit of the character described, including: a body adapted to be secured to a string of drill pipe, said body having a cutter recess formed between relatively inner and outer walls, there being slots across the outer ends of said Walls on an axis crossing said recess, one of said slots having substantially p arallel side walls; a roller type cutter in said recess having a shaft opening therethrough; a shaft for said cutter comprising a cylindrical bar with the end portions' thereof flattened and resting in said slots in a non-rotatable manner; and a rivet extending through one of said walls and the slot therein in a position to hold the end of said shaft in said slotl in close proximity to the upper wall of said slot, said rivet having a head formed on one end thereof adapted` to be removed to permit removal thereof.

10. A bit of the character described, including: a body adapted to be secured to a string of drill pipe, said body having a cutter recess formed between relatively inner and outer walls, there being slots across the outer ends of said walls on anv axis crossing said recess, one of said slots having substantially parallel side walls; a roller type cutter in said recess having a shaft opening therethrough; a shaft for said cutter comprising a cylindrical bar with the end portions thereof flattened and resting in said slots in a, non-rotatable manner, there being shoulders formed o'n said shaft to transmit forces from said shaft to said body in a direction essentially parallel to the axis of said shaft; and a rivet extending through one of said walls and the slot therein in a position to hold the end of said shaft in said slot in close proximity to the upper wall of said slot, said rivet having a head` formed on o ne end thereof adapted to be removed to permit removal thereof.

11. An earth boring roller cutter of the character described for use with a bit body having a cylindrical bearing member and roller members disposed around said bearing member, comprising a circular body having peripheral cutting means and a bore to receive said bearing member, there being a counterbore extending from one end of said circular body to a. point near the opposite end thereof to receive said roller members.

l2. A bearing for a roller cutter of the character described, comprising: a shaft: a cutter body on said shaft, said cutter body having a bearing bore of larger diameter than said shaft and an inwardly projecting radial ange at ,an end of said bearing bore, the inner portion of said flange approaching close to the surface of said shaft; and bearing rollers in said bearing bore abutting the inner radial face of said flange, there being a plate closing the open end of said bearing bore.

13. A bit of the character described, including: a. body adapted to be secured to the lower end of a string of drill pipe, saidy body having a slot formed between inner and outer walls; a cutter shaft extended across said slot between said inner and outer Walls; and a roller cutter mounted on said shaft, said roller cutter having a bore of a size to closely t said shaft and having a counterbore extending from one end of said roller cutter to a point near the opposite end thereof, there being bearing rollers disposed around and in engagement with said shaft within said counterbore and abutting the inner end wall of said counterbore.

14. A bit of the character described, including: a body adapted to be secured to the lower end of a string of drill pipe, said body having a' slot formed between inner and vouter walls; a cutter shaft extended across said slot between said inner and outer walls; a roller cutter mounted on said shaft, said roller cutter having a. bore of a size to closely t said shaft and having a counterbore extending from one end of said roller cutter to a point near the opposite end thereof, there being bearing rollers disposed around and in engagement with said shaft within said counterbore and abutting the inner end wall of said counterbore; and a thrust plate on said shaft in position to close the open end of said counterbore and to receive the wear of the ends of said bearing rollers.

15. A-bearing for a roller cutter of the character described, comprising: a shaft; a cutter body on said shaft, said cutter body having a bearing bore of larger diameter than said shaft and an inwardly projecting radial flange at an end of said bearing bore; and bearing rollers in said bearing bore abutting the inner face of said flange, there being a. plate closing the open end 0f said bearing bore.

16. An earth boring roller cutter of the character described for use with a bit body having a cylindrical bearing member and roller members disposed around said bearing member, compris- 'ing a circular body having peripheral cutting means and a. bore to receive said bearing member, there being a counterbore extending from one end of said circular body to a point near the opposite end thereof to receive said roller members, the radial depth of said counterbore being at least half the diameter of one of said roller members.

17., An earth boring roller cutter of the character described for use with a bit body having a bearing member and. bearing rollers disposed around said bearing member, comprising a circular body having peripheral cutting means, a bore to receive said bearing rollers, and a radial ange projecting inwardly at one end of said bore for limiting axial movement of said bearing rollers in one direction.

ANTHONY E. CARLSON.

CERTIFICATE 0F CORRC'l-"IOv Patent No. 1,996,322. April 2, 1935.

ANTHONY E. CARLSON.

It is hereby ,certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, second column, line 27, claim 4, after "around" insert the words and in engagement with; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st" day of May, A. D. 1935.

Leslie Frazer (Seal) v Acting Commissioner of Patents. 

